new images obtained by nbc news inside the nursing home. torn up by last week's explosion. >> it was just black smoke, windows all blown out. i thought, my god, what has happened? >> reporter: the administrator wants the world to know of the heroic efforts by the employees and first responders who rushed to pull 130 elderly residents from the rubble. >> has it sunk in yet? >> no. not really. >> reporter: you can hear the panic in the 911 calls. >> look, our house, our whole windows, everything, it sounded like a bomb on 35. i don't know what's going on. >> investigators say they found the origin of the explosion. but won't say where it is. and they still aren't sure what caused wednesday's initial fire. >> we do not have a time line. >> reporter: the fertilizer's facility owner is working closely with investigators and pledges to do everything it can to understand what happened. but already some lawmakers are asking whether chemical storage regulations need to be strengthened. residents wonder how long it will take to rebuild. >> there is a